1. Field of the Invention
This invention relates to a reactor of moving bed type wherein various reactions and adsorptions for the removal of dusts, SOx and NOx are carried out by contacting a gas such as waste gases containing SOx and NOx passing through a louver with a granular material such as carbonaceous adsorbents supported by the louver and moved downward.
2. Description of the Prior Art
In an apparatus of this type, as shown in FIG. 1 of the prior art, granular material 2 is packed and held by a pair of louvers 1 and 1' arranged vertically and is moved downward to form a moving bed, while gas 3 is introduced into reactor 4, passed transversely through the moving bed via louver 1 to effect dust removal and reactions, and then discharged from louver 1' on the opposite side. However, such a reactor has hitherto met with the following problems.
The first problem is that the non-moved part 2-a of granular material 2 is formed on louver 1 as shown in FIG. 2 and accordingly, in the case of feeding a gas with a high dust concentration, a layer of dust grows at the gas inlet side of non-moved layer 2-a, resulting in increase of the pressure loss. In addition, non-moved layer 2-a reaches a saturation in chemical reactions and chemical products come out of non-moved layer 2-a which often corrode the louver and decrease the whole reaction capacity.
Secondly, the exhaust port of granular material 2 in the reactor is ordinarily contracted more narrowly than the gap of louvers 1 and 1' as shown in FIG. 3 and when operated as such, the velocity distribution of the granular material in the moving bed becomes as shown by patterns 5-1 to 5-4 of FIG. 3. Thus, there has been proposed a method wherein various flow regulations 6 as shown in FIG. 4 are provided so as to make the velocity distribution in the moving bed as uniform as possible. However, it is very difficult to control the moving state of the granular material because of the intrinsic non-uniformity thereof and changes in grain size, dust content. Thus, moisture content with the passage of time and the difficulty cannot be overcome only by the provision of the flow regulator.
From the standpoint of dust removal and reactions, on the other hand, granular material 2 in the moving bed is more loaded, in general, nearer the gas inlet side and subjected to the maximum load near the louver at the gas inlet side. When a reaction product is of a strong adhesiveness, granular material 2 tends to agglomerate at a low moving velocity and grows to increase the pressure loss of a gas. In order to avoid this phenomenon, it is preferable to move and replace the granular material at this site at a relatively higher speed. However, the prior art method has no countermeasure and leaves the material alone and unchecked and cannot freely control the moving velocity at the site.